Stars such as Ashton Kutcher, Britney Spears and the Jonas Brothers were among stars who retweeted information about the donation drive.

NEW YORK -- Social gaming firm Zynga's initiative to help raise money for Japan earthquake relief efforts has exceeded $2.2 million in donations to date.

Late on the day of the Japan earthquake/tsunami, the largest social game developer launched a donation initiative with Save the Children's Japan Earthquake Tsunami Children in Emergency Fund across eight games. It then also added Direct Relief International as a partner for relief donations.

Within the first 36 hours, Zynga players raised more than $1 million, and now the company's effort has exceeded the $2.2 million mark, a Zynga representative told The Hollywood Reporter.

Zynga players can donate by buying virtual items in games - with 100 percent of the purchase price going to the fund.

Early last week, it used the help of entertainment industry folks to get the word out about it. Ashton Kutcher, Britney Spears, John Legend, Enrique Iglesias, the Jonas Brothers and Nicky Minaj were among those who retweeted information about the donation drive in a push that led to more than 6,400 tweets with a reach of 34 million followers.

Among other Zynga games with virtual goods benefiting the Japan effort, Café World allows players to place Japanese inspired decorations in their cafes, FrontierVille lets players buy a limited edition Kobe cow to place in their frontier, and FarmVille allows players to plant a limited edition daikon radish crop that never withers.